Sergeant Keith Newell, of Queenstown said the crash happened on a blind bend.
“An overseas driver driving towards Queenstown has fallen asleep at the wheel and had a head on collision with another vehicle [being] driven by an American tourist.
“It very easily could have been a fatal.”
Airbags were deployed in the Toyota Rav4 and the Toyota Corolla, both of which are understood to be rental vehicles.
Emergency services were called to the scene about 5.45pm.
Sgt Newell said the driver was brought to Queenstown police station where he was charged with two counts of alleged careless driving causing injury.
Two people in the other vehicle suffered bruising from wearing their seatbelts.
They will appear in court on January 4.
While no-one was injured and the road was not blocked, the crash did cause a transformer to topple from the pole, the spokeswoman said.
A Network Waitaki spokesman said one person had lost power as a result of the incident, but staff would work on trying to restore power today.
